<p> The [https://www.ontario.ca/laws/regulation/120332 Ontario building code (OBC)] requires only that water collected from rooftops be "free of solids" for irrigation use in an external system such as a rain barrel. </p> | <p> The [https://www.ontario.ca/laws/regulation/120332 Ontario building code (OBC)] requires only that water collected from rooftops be "free of solids" for irrigation use in an external system such as a rain barrel. </p> |